Drive system

Abstract

A drive system for driving accessories associated with the engine of a vehicle and controlled by the speed of the engine crankshaft, constructed such that the rpm of each accessory is substantially constant over at least the major portion of the normal vehicle operating range regardless of increase in the rpm of the engine and its crankshaft. The drive is so constructed that the input rpm to each accessory increases at substantially the same rate as the rpm of the crankshaft to a first, predetermined speed; then the input to each accessory is substantially constant thereafter regardless of increasing engine speed to a second predetermined crankshaft speed. This second predetermined speed preferably corresponds essentially to the established national speed limit.

I claim: 
     
       1. Apparatus for driving accessories (and adapted to be) disposed between a drive shaft connected to an engine in a vehicle and a driven shaft connected to one or more accessories; the combination comprising: a first variable pulley rotationally associated with the drive shaft and having a fixed flange (adapted for connection) connected to the drive shaft and a movable flange movable axially of said fixed flange and the drive shaft;   means for moving said movable flange axially away from said fixed flange above a predetermined speed above zero speed of the drive shaft;   said moving means comprising a disc spring (adapted to bias) biasing said movable flange and centrifugally responsive means associated with said disc spring actuated by centrifugal force above (the) said predetermined speed of the drive shaft to change the bias of said spring and effect movement of said movable flange;   a second variable pulley rotationally associated with the driven shaft and the accessories and having a fixed flange (adapted for connection) connected to the driven shaft and a movable flange movable axially of said fixed flange and said driven shaft;   disc spring means urging said movable flange of said second pulley axially toward said fixed flange thereof;   drive means between said variable pulleys effective to provide the drive therebetween with the drive ratio between the pulleys (being) determined by the position of the movable flanges with respect to their respective fixed flanges;   said apparatus being constructed and arranged to provide substantially a fixed ratio drive between the (driving) drive and driven shafts at relatively low (driving) drive shaft speeds and also to provide substantially a constant speed of the driven shaft for speeds for the (driving) drive shaft above said predetermined speed thereof throughout the major portion of the normal vehicle operating range.   
     
     
       2. Apparatus as recited in claim 1, wherein said drive means comprises a flexible belt. 
     
     
       3. Apparatus as recited in claim 1 wherein said disc spring and said disc spring means are conical and each has an h/t ratio of about 1, where h is the initial formed height and t is the thickness thereof. 
     
     
       4. Apparatus as recited in claim 3 wherein the spring rate curve is continuously positive in slope. 
     
     
       5. Apparatus as recited in claim 1 wherein said drive spring is coupled to said drive shaft and said disc spring means is coupled to said driven shaft. 
     
     
       6. Apparatus as recited in claim 1 wherein said disc spring and said disc spring means have a plurality of radially inwardly extending fingers. 
     
     
       7. Apparatus as recited in claim 1 wherein said disc spring is pre-loaded to a first deflection position, so that centrifugal force on said weights acts at said first predetermined drive shaft speed and said deflection increases as said weights move outwardly. 
     
     
       8. Apparatus as recited in claim 1 wherein said disc spring means is pre-loaded to a deflection to urge said movable flange toward the fixed flange of said second pulley, which deflection decreases as said weights move outwardly. 
     
     
       9. Apparatus as recited in claim 1 further comprising stop means limiting the outward movement of said weights at a second determined speed of said drive shaft, which speed is above said predetermined speed. 
     
     
       10. Apparatus as recited in claim 9 wherein said drive and driven shafts are coupled to rotate at a second fixed ratio at said second determined speed of said drive shaft. 
     
     
       11. Apparatus as recited in claim 10 wherein said apparatus is so constructed and arranged that said second fixed ratio is different from the first named fixed ratio. 
     
     
       12. A drive mechanism adapted to transmit drive between a drive shaft and a driven shaft comprising: a first variable pulley adapted to be rotationally associated with the drive shaft and having a fixed flange adapted for connection to the drive shaft and a movable flange movable axially of said fixed flange and the drive shaft;   means for moving said movable flange axially away from said fixed flange above a predetermined speed above zero speed of the drive shaft;   said moving means comprising a disc spring and centrifugally responsive means associated with said disc spring actuated by centrifugal force above the predetermined speed of the drive shaft to change the loading of said spring and effect movement of said movable flange;   a second variable pulley adapted to be rotationally associated with the driven shaft and having a fixed flange adapted for connection to the driven shaft and a movable flange movable axially of said fixed flange and said driven shaft;   disc spring means urging said movable flange of said second pulley axially toward said fixed flange thereof;   said variable pulleys being adapted to be drivingly connected, the drive ratio between the pulleys being determined by the position of the movable flanges with respect to their respective fixed flanges;   whereby said apparatus provides a substantially constant speed of the driven shaft for speeds of the driving shaft above said predetermined speed thereof throughout the major portion of the normal operating range of speed of said drive shaft.   
     
     
       13. A variable pulley mechanism for use in pulley drive transmissions comprising a fixed flange adapted for connection to a shaft and a movable flange movable axially of said fixed flange and said shaft; means for moving said movable flange axially with respect to said fixed flange above a predetermined speed above zero speed of said shaft;   said moving means comprising a disc spring and centrifugally responsive means associated with said disc spring actuated by centrifugal force above the predetermined speed of the shaft to change the loading of said spring and effect movement of said movable flange;   said disc spring being coupled to said shaft and having a plurality of radially inwardly directed fingers; and   a fulcrum means associated with said shaft having an arcuate fulcrum surface engaging said spring fingers;   said fingers moving relative to said fulcrum surface when the loading on said spring is changed.   
     
     
       14. A variable pulley mechanism as recited in claim 13, further including a plurality of tangs extending between fingers of said spring. 
     
     
       15. In an accessory drive, the combination comprising drive input means associated with and responsive to the speed of a prime mover, drive output means associated with and effective to drive accessories, and speed control means variable in response to the speed of said drive input means (adapted to be) disposed between said drive input means and said drive output means for providing a linear speed drive relationship therebetween below a relatively low and above zero speed of said drive input means and also for providing a controlled variable speed drive relationship therebetween over substantially the normal range of speed of said drive input means in excess of said relatively low speed, the variable speed drive relationship being characterized in that the speed of said drive output means remains substantially constant during the speeds of said drive input means above said relatively low speed over substantially the normal range of speed of said drive input means in excess of said relatively low speed, said speed control means comprising: a first variable pulley rotationally associated with said drive input means and having a fixed flange (adapted for connection) connected to said drive input means and a movable flange movable axially of said fixed flange and said drive input means;   means for moving said movable flange axially away from said fixed flange above said low speed of said drive input means;   said moving means comprising a disc spring and centrifugally responsive means associated with said disc spring actuated by centrifugal force above said low speed of said drive input means to change the loading of said spring and effect movement of said movable flange;   a second variable pulley rotationally associated with said drive output means and said accessories and having a fixed flange (adapted for connection) connected to the drive output means and a movable flange movable axially of said fixed flange and said drive output means;   disc spring means urging said movable flange of said second pulley axially toward said fixed flange thereof; and   means drivingly interconnecting the first and second pulley means, the speed relationship therebetween being determined by said centrifugally responsive means.   
     
     
       16. An accessory drive as recited in claim 15 wherein said drive means comprises a flexible belt. 
     
     
       17. An accessory drive as recited in claim 15 wherein said disc spring and said disc spring means are conical and each has an h/t ratio of about 1, where h is the initial formed height and t is the thickness thereof. 
     
     
       18. An accessory drive as recited in claim 17 wherein the spring rate curve is continuously positive in slope. 
     
     
       19. An accessory drive as recited in claim 15 wherein said disc spring is coupled to said drive input means at its outer periphery and said disc spring means is coupled to said drive output means. 
     
     
       20. An accessory drive as recited in claim 15 wherein said disc spring and said disc spring means have a plurality of radially inwardly extending fingers. 
     
     
       21. An accessory drive as recited in claim 15 wherein said disc spring is pre-loaded to a first deflection position, so that centrifugal force on said weights acts above said low speed of said drive input means and said deflection increases as said weights move outwardly. 
     
     
       22. An accessory drive as recited in claim 15 wherein said disc spring means is pre-loaded to a deflection to urge said movable flange toward the fixed flange of said second pulley, which deflection decreases as said weights move outwardly. 
     
     
       23. An accessory drive as recited in claim 15 further comprising stop means limiting the outward movement of said weights at a second speed of said drive input means which speed is above said first named speed. 
     
     
       24. An accessory drive as recited in claim 23 wherein said input drive means and output drive means are coupled to rotate at a second fixed ratio at said second speed of said input drive means. 
     
     
       25. An accessory drive as recited in claim 24 wherein said apparatus is so constructed and arranged that said second fixed ratio is different from the first named fixed ratio.